Polycrystalline silicon rods are conventionally cut by a rotating saw comprising a rotating saw such as a diamond wheel. Usual polycrystalline silicon rods have a diameter of 50-150 mm, and the cutting speed by the rotating saw is 5-15 mm/min. Therefore, considerable time is required to cut a rod into a plurality of shorter lumps. The recent trend toward producing silicon rods in larger diameters makes it particularly important to expedite the cutting of silicon rods.
We have found that a polycrystalline silicon rod can be easily cut if pressing forces are applied on a plane perpendicular to the longitudinal axis of the silicon rod toward the axis of the rod at evenly located positions on the periphery of the rod by means of wedge edges. This invention was accomplished on the basis of this finding.